JP5831072B2 - Manufacturing method of molten metal plated steel strip - Google Patents

Description

  The present invention relates to a method for producing a molten metal-plated steel strip that can reduce splash defects not only at a normal plate passing speed but also at a high plate passing speed in a molten metal plating process.

  In a continuous hot dipping process or the like, as shown in FIG. 5, the steel strip S is generally immersed in a plating bath 8 filled with molten metal and the direction is changed by the sink roll 7. After the step of pulling upward, the steel strip width provided facing the steel strip S so that the molten metal adhering to the steel strip surface has a predetermined plating thickness uniformly in the plate width direction and the plate longitudinal direction. There is provided a gas wiping device that jets pressurized gas from the wiping nozzle 1 extending in the direction onto the steel strip, squeezes excess molten metal, and controls the amount of adhesion of the molten metal (plating amount). .

  The wiping nozzle 1 is usually longer than the steel strip width, that is, extending beyond the width end of the steel strip S, in order to cope with various steel strip widths and at the same time, the deviation in the width direction when the steel strip is pulled up. Yes. In such a gas wiping system, a molten metal falling downward due to the turbulence of the jet impinging on the steel strip S scatters around it, so-called splash adheres to the steel strip S, and the surface quality of the steel strip is generated. Cause a decline.

  Moreover, in order to increase the production amount in the continuous process, the steel plate passing speed may be increased. However, in the case of controlling the coating amount by the gas wiping method in the continuous hot dipping process, due to the viscosity of the molten metal, As the steel strip passing speed increases, the initial deposit immediately after passing through the plating bath of the steel strip increases, so to control the plating deposit within a certain range, the wiping gas pressure must be set higher. Not resulting in a significant increase in splash and inability to maintain good surface quality.

  In order to solve the above problems, the following inventions are disclosed.

  In Patent Document 1, as shown in FIG. 6, a metal plate 24 is installed between the wiping gas supply main pipe 21 and the wiping nozzle 23, and a filter 26 is provided between the wiping gas supply main pipe 21 and the alloying furnace 25. Installed along the steel sheet S. When the plating metal splash (splash) generated on the plating bath surface 27 goes around the outside of the wiping nozzle 23 toward the steel plate S after wiping, the splash adheres to the steel plate S by removing it with the filter 26. To prevent. A gas supply pipe 22 connects the wiping gas supply main pipe 21 and the wiping nozzle 23.

  In Patent Document 2, as shown in FIG. 7, by providing a rectifying plate 32 projecting to the rear of the wiping nozzle 31 and a weir 33 on the front portion on the wiping nozzle 31, the splash 34 on the plated steel strip S is provided. A method for preventing adhesion is disclosed.

  In Patent Document 3, as shown in FIG. 8, a splash adsorbent 44 made of fibrous or non-woven fabric having a melting point of 450 ° C. or lower is provided on the gas supply pipe 43 from the header pipe 41 to the wiping nozzle 42 and / or the main body of the wiping nozzle 42. A method for preventing the adhesion of the splash to the plated steel strip S by disposing and adsorbing the splash with the splash adsorbent 44 is disclosed.

JP-A-5-306449 JP 2000-328218 A JP 2009-167455 A

  However, in the method disclosed in Patent Document 1, when the mesh of the filter 26 is increased, the effect of the filter 26 is lost, and when the mesh is decreased, the splash around the outside of the filter 26 is prevented from adhering to the metal plate 24. The splash that has entered directly between the filter 26 and the metal plate 24 without rotating around the back surface of the wiping nozzle 23 is less likely to be discharged out of the filter 26, and thus the effect of preventing the occurrence of splash defects is insufficient. I understood.

  In the method disclosed in Patent Document 2, it is not possible to prevent splash splashing around the back surface of the wiping nozzle 31 from adhering to the plated steel strip and projecting to the rear of the wiping nozzle 31 during operation. Splash (metal powder) deposited on the flow straightening plate 32 is re-scattered by a change in the wiping gas flow due to a change in wiping conditions (wiping gas pressure, nozzle height, etc.), and this phenomenon takes time. As a result, it became apparent that the splash adhesion could not be prevented stably.

  In the method disclosed in Patent Document 3, the collection of the splash is good at the beginning, but the portion where the splash is once attached is not collected when the splash comes after that. It is the steel strip edge portion that generates and scatters a particularly large amount of splash. Therefore, the splash tends to adhere to the splash adsorbent 44 at a position corresponding to the steel strip edge portion. Since it is difficult to replace the splash adsorbent 44 during operation, the splash trapping effect is effective for a short period of time (1) after installing the splash adsorbent 44 in the case of normal operation (120 to 150 mpm) of a continuous hot dip galvanizing line. Only about a week).

  The present invention solves the above-mentioned problems, and in the case where not only the normal plate passing speed but also the plate passing speed is increased, the occurrence of splash defects is suppressed for a long period of time, and a molten metal plated steel strip excellent in surface quality is obtained. The purpose is to enable stable production.

  Means of the present invention for solving the above-mentioned problems are as follows.

  [1] Molten metal plated steel strip that controls the thickness of the deposited metal by blowing gas from a wiping nozzle that is disposed opposite to both surfaces of the steel strip that is continuously pulled up from the molten metal plating bath. In the manufacturing method of the first aspect, the first charging structure having a plurality of openings above or on the rear surface of the wiping nozzle and charged to a positive charge or a negative charge is placed on the bath at a height in the vertical direction from the upper surface of the wiping nozzle. A method for producing a hot-dip metal-plated steel strip, characterized by being installed so as to extend in the width direction of the steel strip so as to be in the region up to the height position of the support roll.

  [2] A second charging structure that has a plurality of openings and is charged to a charge opposite to that of the first charging structure. The vertical position of the second charging structure is that of the first charging structure. The production of the hot-dip galvanized steel strip according to the above [1], wherein the steel strip extends in the width direction of the steel strip so as to be in the region from the upper end to the height position of the bath support roll. Method.

  [3] The method for producing a hot-dip metal-plated steel strip according to [1] or [2], wherein the first charging structure is a belt-like body having an aperture ratio of 20 to 80%.

  [4] The method for producing a hot-dip metal-plated steel strip according to [2] or [3], wherein the second charging structure is a belt-like body having an aperture ratio of 20 to 80%.

  [5] The molten metal plated steel strip according to any one of [1] to [4], wherein the first charging structure and the second charging structure are charged by a static electricity generator. Manufacturing method.

  [6] The method for producing a molten metal-plated steel strip according to any one of [1] to [5], wherein the wiping nozzle and the first charging structure are electrically insulated.

  According to the present invention, by installing a positively or negatively charged charging structure above the wiping nozzle, it is possible to collect splash for a long period of time not only when the plate passing speed is increased but also when the plate passing speed is increased. Therefore, the occurrence of splash defects can be suppressed, and a molten metal plated steel strip having excellent surface quality can be stably manufactured.

It is a side view which shows embodiment of the gas wiping apparatus used for implementation of this invention. It is a figure which shows the splash scattering path | route around a wiping nozzle. It is a figure which shows an example of embodiment of the charging structure used for implementation of this invention. It is a figure which shows the relationship between the aperture ratio of a charging structure, and a splash collection rate. It is a schematic side view of the manufacturing apparatus of a general continuous molten metal plating steel strip. It is a figure which shows the principal part of the gas wiping apparatus used by patent document 1. FIG. It is a figure which shows the principal part of the gas wiping apparatus used by patent document 2. FIG. It is a figure which shows the principal part of the gas wiping apparatus used by patent document 3. FIG.

  When manufacturing a molten metal-plated steel strip, pressurized gas is blown onto the steel strip surface from a wiping nozzle that is placed opposite to both sides of the steel strip on the surface of the steel strip that is continuously pulled up from the molten metal plating bath. To control the thickness of the deposited metal. At this time, there is a problem that splash of molten metal scatters, and the scattered splash adheres to the steel strip and deteriorates the surface quality of the steel strip.

  The present inventors examined a method for collecting splashed splash (metal powder). As a result, it has been found that the splash is attracted to a positively or negatively charged object even though it has a certain speed. In addition, the charged structure is placed above or on the back of the wiping nozzle in consideration of the splash scattering path, and the structure has an opening so that the splash generated during wiping can be captured. It has been found that the collecting effect can be maintained for a long time, and defects due to splash adhesion can be significantly reduced.

  In the present invention, the vertical structure has a vertical wiping position of a charging structure (first charging structure) that has a plurality of openings on the upper side or the rear side of the wiping nozzle and is charged to a positive or negative charge. It is installed so as to extend in the width direction of the steel strip so that it is in the region from the upper surface of the nozzle to the height position of the on-bath support roll. The height position of the bath support roll is the outer peripheral upper end of the bath support roll.

  The first charging structure scatters the splash that moves below the wiping nozzle and rebounds on the bath surface, and then moves around the back surface of the wiping nozzle and moves toward the steel strip. Splashes that move to the steel strip side around the back of the wiping nozzle are often transported to the steel strip side between the upper surface of the wiping nozzle and the wiping gas supply header. Therefore, the first charging structure is wiped by the wiping nozzle. By installing between the upper surface and the wiping gas supply header, it is possible to effectively collect the splash and reduce the occurrence of the splash defect even though the first charging structure has a small size.

  Another charging structure (second charging structure) having a plurality of openings is charged to a charge opposite to that of the first charging structure, and the height position in the vertical direction is the first charging structure. In the region from the upper end of the body to the height position of the bath support roll, and extending in the steel strip width direction, it is possible to further reduce the occurrence of defects due to splash adhesion it can.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side view of a diagram showing an embodiment of a gas wiping apparatus used for carrying out the present invention. In FIG. 1, 1 is a wiping nozzle, 2 is a first charging structure, 3 is a second charging structure, 4 is a wiping gas supply header, 5 is a pressurized gas from the wiping gas supply header 4 to the wiping nozzle 1 ( A gas pipe for feeding a wiping gas), 6 a support roll on the bath, 7 a sink roll, 8 a plating (molten metal bath), and S a steel strip.

  In the apparatus of FIG. 1, the first charging structure 2 is installed between the upper surface of the wiping nozzle 1 and the wiping gas supply header 4, and is installed closer to the steel strip than the gas pipe 5. One end of the second charging structure 3 is disposed close to the on-bath support roll 6, the other end is disposed close to the wiping gas supply header 4, and the height in the vertical direction is the first height structure. It exists in the area | region from the upper end part of the charging structure 2 to the height position of the support roll 6 on a bath. The first charging structure 2 and the second charging structure 3 are installed so as to extend in the steel strip width direction, and the length thereof is approximately the same as the width of the wiping nozzle.

  The first charging structure 2 and the second charging structure 3 are formed of a belt-like body having a plurality of (many) openings, and are charged with positive charges or negative charges. However, the second charging structure 3 is charged to a charge opposite to that of the first charging structure 2. Examples of the belt-like body having a plurality of (many) openings include, but are not limited to, a net-like belt-like body and a punch sheet.

  The apparatus of FIG. 1 includes the first charging structure 2 and the second charging structure 3 to collect splash generated during gas wiping and prevent the occurrence of splash defects for a long period of time. it can. This point will be further described.

  FIG. 2 is a schematic view showing an example of a splash scattering path in the gas wiping apparatus. Dotted arrows in the figure indicate splash splash paths. Splash of the molten metal is generated by the turbulence of the jet flow ejected from the wiping nozzle 1 and colliding with the steel strip S. Usually, a lot of splashes are scattered below the wiping nozzle 1 as in the paths (A) and (B), a part of which splashes back on the bath surface and soars due to the gas flow flowing upward on the back surface of the wiping nozzle 1. As shown in (a), it goes around the back surface of the wiping nozzle 1 and passes between the gas pipes 5 (in many cases, a plurality of pipes are arranged at an appropriate pitch in the width direction of the steel strip) and enters the nozzle upper surface side, It adheres to the steel strip S as in the path (f), or ascends to the vicinity of the upper support roll 6 on the upper bath around the back surface of the wiping gas supply header 4 and adheres to the steel strip S as in the path (b). To do. There are more splashes that move toward the steel strip along the path (A) than rushes that move toward the steel strip along the path (B).

  Splash generated by the interference of the wiping gas injected from the opposing wiping nozzle at the edge of the steel strip is scattered to the upper surface side of the wiping nozzle 1 as in the path (c), and the upper surface of the wiping nozzle 1 or the gas pipe. It sticks to 5 or bounces without sticking. Some splashes are directly attached to the steel strip S. Further, the splash splashed and rolled down on the upper surface of the wiping nozzle 1 and scattered upward along the steel strip S by the upward flow of the wiping gas after colliding with the steel strip S as in the path (d). It adheres, rebounds like a path (e), returns to the upper part of the wiping nozzle 1, and adheres to the steel strip S as the path (f).

  In order to prevent the splash from adhering to the steel strip S, it is most important to reduce the splash that travels around the back surface of the wiping nozzle 1 and moves to the steel strip side in the route (A). ) To reduce the splash moving to the steel strip side, preventing the wiping gas injected from the opposing wiping nozzle 1 from interfering with the steel strip edge portion and preventing the splash generated from adhering to the steel strip, and After the splash that has risen along the steel strip S by the upward flow of the wiping gas and bounced off the support roll 6 on the bath returns to the upper side of the wiping nozzle 1, it adheres to the steel strip S through the paths (e) and (f). It is desirable to be able to prevent this.

  If the band-like structures (the first band-like structure 2 and the second band-like structure 3) are band-like bodies having no opening, the gas flow is a flow along the band-like structure or a countercurrent after collision. The splash is difficult to access the band-like structure. Therefore, even if the charging structure is charged, splash cannot be efficiently adsorbed and collected by the charging structure. By providing the charging structure with an opening, the gas flow can easily pass through the band-shaped structure, so that the splash can easily approach the band-shaped structure. Since the belt-like structure is charged, the splash can be efficiently adsorbed and collected on the charged structure. Since the splash adsorbed on the band-shaped structure is charged with the same charge as that of the charged structure, even if the splash is adsorbed on the charged structure, the splash adsorption effect of the charged structure does not decrease. As a result, a good splash adsorption / collection effect can be maintained stably for a long period of time. In addition, since the band-shaped structure has an opening, even if the band-shaped structure is installed, there is little influence on the wiping gas flow, and it is possible to control the amount of plating adhesion under the wiping conditions almost the same as the conventional wiping conditions. There are also advantages.

  The first charging structure 2 collects the splash that moves to the steel strip side after turning around the back surface of the wiping nozzle 1 in the path (A). The first charging structure 2 further includes a splash of the path (c) (splash generated by the wiping gas interfering at the edge of the steel strip) and a splash of the path (e) (bounce back by the support roll 6 on the bath). There is also an effect of collecting a splash that moves upward of the wiping nozzle 1.

  It is preferable that the first belt-like structure 2 is arranged while ensuring electrical insulation with the wiping nozzle 1. The first band-shaped structure 2 can be disposed with a gap sufficient to ensure insulation from the wiping nozzle 1, but it is preferable to secure insulation by disposing an insulator therebetween. As for the 1st strip | belt-shaped structure 2, it is desirable to ensure the insulation similar to the wiping nozzle 1 also in the wiping gas supply header 4 and the gas piping 5. FIG.

  FIG. 3 shows an example of an embodiment of the first charging structure band 2 used in the apparatus of FIG. In order to charge the first charging structure 2, a commercially available corona discharge device 10 or the like may be installed in the vicinity of the structure 2 and charged, or another means may be used. For the sign of the charge, a generally known charge train may be referred to. For example, when the plating metal is zinc, it has a positive charge with respect to the surrounding steel material. The structure 2 may be provided with a negative (minus) charge. If the charge amount is too large, discharge from the first charging structure 2 occurs. If the charge amount is too small, the splash collecting ability is lowered. Therefore, the first charging structure 2 may be appropriately charged to a charge amount. By appropriately installing a charge sensor (potential sensor) 11 for charge amount control, it is possible to operate while monitoring the charge amount. The arrows in FIG. 3 indicate the discharge direction.

  The first charging structure 2 can also be disposed on the back side (anti-steel strip side) of the wiping nozzle 1. In this case, it is preferable to install the lower end of the first charging structure 2 in the vicinity of the rear portion (anti-steel strip side) of the wiping nozzle 1 and on the back side (anti-steel strip side) of the gas pipe 5.

  In order to collect more splashing splashes, it is desirable to install the second charging structure 3 above the first charging structure 2.

  In the apparatus of FIG. 1, the second charging structure 3 has one end close to the outer peripheral surface of the on-bath support roll 6 and the other end close to the wiping gas supply header 4, and the wiping gas supply header 4 and the on-bath support. It is installed between the rolls 6. The second charging structure 3 is charged with a charge opposite to that of the first charging structure 2. The second charging structure 3 is arranged with electrical insulation from the on-bath support roll 6. The second charging structure 3 can be arranged with an interval sufficient to ensure insulation from the on-bath support roll 6, but it is preferable to arrange an insulator between them. It is desirable for the second charging structure 3 to ensure the same insulating property as that of the on-bath support roll 6 for the wiping gas supply header 4.

  The second charging structure 3 collects the splash that moves to the steel strip side after turning around the back surface of the wiping nozzle 1 in the path (b), and further, the splash (path on the bath support roll) 6), the splash that moves up the wiping nozzle 1 after rebounding at 6 is collected. In addition, the splash that has passed through the vicinity of the second charging structure 3 but not collected by the second charging structure 3 is given a charge opposite to that of the first charging structure 2. Thereafter, the first charging structure 2 has an effect that the splash is easily collected.

  The splash of the path (b) does not pass through the second charging structure 3, does not move between the second charging structure 3 and the on-bath support roll 6, and moves to the steel strip side. After the splash of (e) rebounds on the bath support roll 6, the wiping nozzle 1 passes between the second charge structure 3 and the bath support roll 6 without passing through the second charge structure 3. If the second charging structure 3 does not move upward, the second charging structure 3 may be disposed at a certain distance from the on-bath support roll 6, or the second charging structure 3 may be disposed on the on-bath support roll 6. It may be arranged at a lower position.

  The second charging structure 3 has the same configuration as the first charging structure 2 described above, and can be charged by the same method. However, the charge is opposite to that of the first charging structure 2.

  Since the first charging structure 2 and the second charging structure 3 have the effects as described above, the first charging structure 2 can be installed for gas wiping to provide a good splash for a long time. The adsorption / collection effect can be maintained, and further, by installing the second charging structure 3 and performing gas wiping, a better splash adsorption / collection effect can be maintained for a long period of time. As a result, the occurrence of defects due to splash adhesion can be significantly reduced.

  The first charging structure 2 is arranged so that the upper end of the first charging structure 2 is above the wiping gas supply header 4, and the first charging structure 2 causes the path (A) and path (B) to move toward the steel strip. You may make it collect the splash which moves. When the first charging structure 2 and the second charging structure 3 are disposed close to each other, the first charging structure 2 and the second charging structure 3 are to ensure electrical insulation. To place. It is preferable to secure insulation by disposing an insulator between the two.

  Splashes adsorbed and collected by the first charging structure 2 and the second charging structure 3 are temporarily discharged using a static eliminator when the operation is stopped, such as changing the roll in the bath, and sucked like a vacuum cleaner. By using means, it can be easily removed by suction.

  A simple experiment was conducted to investigate the aperture ratio optimization of the charging structure. Zinc powder with a diameter of φ0.05 to 0.5 mm is put into an air flow with a wind speed of 1 m / s, and a plastic sheet having various aperture ratios is charged on the downstream side by charging to −50 kV to collect the zinc powder. FIG. 4 shows the result of the experiment. The collection rate is the ratio (%) of the weight of the zinc powder adhered to the plastic sheet to the weight of the charged zinc powder. The collection rate is 50% or more when the aperture ratio of the charging structure is 20 to 80%, and the collection rate is 80% or more when the aperture ratio is 40 to 70%. From this result, the aperture ratio is preferably 20 to 80%, and more preferably 40 to 70%. Further, when the size of the opening is reduced, clogging is likely to occur. When the size of the opening is increased, the passing rate of the metal powder is increased and the adsorption ability is reduced. Therefore, the short side dimension (minimum dimension) is 0.5 mm or more and long The side dimension (maximum dimension) is preferably 3 mm or less (in the case of a circular hole, the diameter is preferably 0.5 to 3 mm), and one side is preferably 0.5 to 3 mm.

  The cross-sectional shapes of the first charging structure 2 and the second charging structure 3 (the shape of the vertical cross section perpendicular to the steel strip surface) are not particularly limited. Either a straight line or a curve may be used, or a combination of both may be used.

  When the wiping nozzle 1 is charged, the metal powder tends to adhere to the nozzle, and the nozzle is clogged. From this point, the wiping nozzle 1 is preferably grounded.

  In order to clarify the effect of the present invention, the gas wiping apparatus shown in FIG. 1 was installed in a continuous hot dip galvanizing line, and an experiment for manufacturing a hot dip galvanized steel strip was conducted.

  The first charging structure 2 and the second charging structure 3 are both composed of a heat-resistant resin sheet (thickness 1 mm), holes of φ1.5 mm are regularly arranged, and the aperture ratio is 62 0.0%. The length in the steel strip width direction was the same as the length of the wiping nozzle 1 in the steel strip width direction. The length of the vertical cross section perpendicular to the steel strip surface is the same length as the gas pipe 5 in the first charging structure 2, and the wiping gas supply header 4 and the on-bath support roll 6 are in the second charging structure 3. It was set to 300 mm, which is almost the same length as the interval. Each of the first charging structure 2 and the second charging structure 3 has a structure as shown in FIG. 3, and a corona discharge device and a charge removal device (not shown) are installed at the end in the width direction. A charge sensor was installed at the center in the width direction. During operation, the discharge device was controlled such that the first charging structure 2 was maintained at approximately -50 kV and the second charging structure 3 was maintained at approximately +50 kV. When the experimental conditions were changed, the first charging structure 2 and the second charging structure 3 were neutralized by the static eliminator, and then the collected splash was removed. As a comparative example, the splash adhesion preventing method of the prior art 1 or 3 was carried out.

The manufacturing conditions were as follows: slit gap of wiping nozzle: 0.9 mm, wiping nozzle-steel strip distance: 8 mm, nozzle height from molten zinc bath: 500 mm, molten zinc bath temperature: 460 ° C., plating adhesion amount 45 g / side It was m ^2. Table 1 shows the other manufacturing conditions and the results of investigation of the splash occurrence rate. Splash occurrence rate starts after maintenance of equipment, and on the 1st and 15th day, steel strip size is 0.8mm thickness x 1.2m width 3 to 5 coils for each production condition (through plate The speed is the ratio of the length of the steel strip that has been passed through the target coil and the length of the steel strip that has been judged to have a splash defect in the inspection process. Contains minor splash defects. For the condition with many splash defects on the first day, the experiment up to the 15th day was not conducted.

  In the normal plate feed speed of 150 mpm, the first and second embodiments of the present invention are maintained at a low level of splash defects both on the first day of operation and on the fifteenth day. The incidence of splash defects is lower. On the other hand, in Comparative Example 3, the splash defect occurrence rate on the first day of operation is slightly inferior to that in Example 1, but on the 15th day, the splash defect occurrence rate is significantly increased. Defects cannot be prevented stably over a long period of time. In Comparative Examples 1 and 2, the incidence of splash defects is inferior to Examples 1 and 2 of the present invention from the first day of operation.

  Even when the plate passing speed is increased to 180 mpm, in Example 3 of the present invention, the incidence rate of splash defects is maintained at a low level on both the first day and the fifteenth day of operation. On the other hand, in Comparative Examples 4 and 5, the incidence of splash defects was remarkably increased, so the experiment was stopped halfway.

  According to the present invention, it is possible to maintain the splash collecting effect for a long period of time not only in the case of the normal steel strip passage speed but also in the case of increasing the steel strip passage speed, thereby suppressing the occurrence of splash defects, This makes it possible to stably produce a hot-dip metal-plated steel strip.

S Steel strip 1 Wiping nozzle 2 First charging structure 3 Second charging structure 4 Wiping gas supply header 5 Gas pipe 6 Bath support roll 7 Sink roll 8 Plating bath 10 Corona discharge device 11 Charging sensor (potential sensor)
21 Wiping gas supply main pipe 22 Gas supply pipe 23 Wiping nozzle 24 Metal plate 25 Alloying furnace 26 Filter 27 Plating bath surface 31 Wiping nozzle 32 Current plate 33 Weir 34 Splash 41 Header pipe 42 Wiping nozzle 43 Gas supply pipe 44 Splash adsorbent .

Claims (5)

A method for producing a molten metal-plated steel strip in which the thickness of the adhered metal is controlled by blowing a gas from a wiping nozzle disposed opposite to both surfaces of the steel strip that is continuously pulled up from the molten metal plating bath. The first charging structure having a plurality of openings on the upper side or the rear side of the wiping nozzle, which is charged positively or negatively and collects the splash, has a vertical height position on the upper surface of the wiping nozzle. And extending in the width direction of the steel strip so as to be in the region from the height position of the support roll on the bath , having a plurality of openings, and being opposite to the first charging structure The second charging structure that is charged with electric charges and collects the splash has a vertical height position in a region from the upper end of the first charging structure to the height position of the on-bath support roll. Like a steel strip Method for manufacturing a molten metal plated steel strip, characterized in that installed by extending direction. 2. The method for producing a hot-dip metal-plated steel strip according to claim 1, wherein the first charging structure is a belt-like body having an aperture ratio of 20 to 80%. It said second charging structure, manufacturing method of molten metal plated steel strip according to claim 1 or 2, wherein the aperture ratio is strip of 20-80%. The method for producing a molten metal-plated steel strip according to any one of claims 1 to 3 , wherein the first charging structure and the second charging structure are charged by a static electricity generator. The method for producing a molten metal-plated steel strip according to any one of claims 1 to 4 , wherein the wiping nozzle and the first charging structure are electrically insulated.